package com.ciaojian.core.util;

import lombok.extern.slf4j.Slf4j;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Base64;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.Security;
import java.util.Arrays;

/**
 * 微信工具
 *
 * @author oxiny
 */
@Slf4j
public class WeChatUtil {

    public static String decryptData(String encryptDataB64, String sessionKeyB64, String ivB64) {
        log.info("encryptDataB64:" + encryptDataB64);
        log.info("sessionKeyB64:" + sessionKeyB64);
        log.info("ivB64:" + ivB64);
        return new String(
                decryptOfDiyIv(
                        Base64.decode(encryptDataB64),
                        Base64.decode(sessionKeyB64),
                        Base64.decode(ivB64)
                )
        );
    }

    private static final String KEY_ALGORITHM = "AES";
    private static final String ALGORITHM_STR = "AES/CBC/PKCS7Padding";
    private static Key key;
    private static Cipher cipher;

    private static void init(byte[] keyBytes) {
        // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
        int base = 16;
        if (keyBytes.length % base != 0) {
            int groups = keyBytes.length / base + 1;
            byte[] temp = new byte[groups * base];
            Arrays.fill(temp, (byte) 0);
            System.arraycopy(keyBytes, 0, temp, 0, keyBytes.length);
            keyBytes = temp;
        }
        // 初始化
        Security.addProvider(new BouncyCastleProvider());
        // 转化成JAVA的密钥格式
        key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
        try {
            // 初始化cipher
            cipher = Cipher.getInstance(ALGORITHM_STR, "BC");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 解密方法
     *
     * @param encryptedData 要解密的字符串
     * @param keyBytes      解密密钥
     * @param ivs           自定义对称解密算法初始向量 iv
     * @return 解密后的字节数组
     */
    private static byte[] decryptOfDiyIv(byte[] encryptedData, byte[] keyBytes, byte[] ivs) {
        byte[] encryptedText = null;
        init(keyBytes);
        try {
            cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(ivs));
            encryptedText = cipher.doFinal(encryptedData);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return encryptedText;
    }


//    public static JSONObject decryptData(String encryptedData,String sessionKey, String iv) {
//        // 被加密的数据
//        byte[] dataByte = Base64.decode(encryptedData);
//        // 加密秘钥
//        byte[] keyByte = Base64.decode(sessionKey);
//        // 偏移量
//        byte[] ivByte = Base64.decode(iv);
//        try {
//            // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
//            int base = 16;
//            if (keyByte.length % base != 0) {
//                int groups = keyByte.length / base + 1;
//                byte[] temp = new byte[groups * base];
//                org.bouncycastle.util.Arrays.fill(temp, (byte) 0);
//                System.arraycopy(keyByte, 0, temp, 0, keyByte.length);
//                keyByte = temp;
//            }
//            // 初始化
//            Security.addProvider(new BouncyCastleProvider());
//            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding", "BC");
//            SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
//            AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
//            parameters.init(new IvParameterSpec(ivByte));
//            // 初始化
//            cipher.init(Cipher.DECRYPT_MODE, spec, parameters);
//            byte[] resultByte = cipher.doFinal(dataByte);
//            if (null != resultByte && resultByte.length > 0) {
//                String result = new String(resultByte, StandardCharsets.UTF_8);
//                return JSONObject.parseObject(result);
//            }
//        } catch (Exception e) {
//            e.printStackTrace();
//        }
//        return null;
//
//    }
}
